I have far more patience for "um" than for most of these others. I like hesitation words. They occur universally, but with so many charming deviations in each language. I particularly like the Japanese "Ehhhhhhhhh-toooooooooooo" and the French "Euhhhhhhhh".
Granted, they are a mite selfish, since their implied meaning is "I need time to think, but I don't want to leave a silence in which you might interrupt my train of thought," but I consider it an acceptable form of selfishness.
On the other hand "kind of" and "sort of" are falsely self-deprecating, and annoy me deeply. Like, really deeply. ;-)